Sim M F, Stone M, Johansen A, Evans W
Academic Department of Geriatric Medicine, Llandough Hospital, Cardiff, UK.
Technol Health Care. 2000;8(5):277-84.
Measurements of bone density (BMD) are central to the World Health Organisation (WHO) approach to the definition of osteoporosis. Dual energy X- ray absorptiometry (DXA) remains the gold standard technique for measuring the bone mineral density (BMD) but Quantitative Ultrasound (QUS) is an attractive alternative method of bone assessment because it is easy to use and relatively inexpensive. It has been suggested that QUS could be used as a selective population pre-screen, to maximise the cost effectiveness of referral for DXA assessment of BMD. We set out to examine how such an approach might perform in the assessment of women with low trauma Colles' fracture. In 46 women aged 50-80 (mean 67) years we used DXA to measure BMD at lumbar spine and hip, and heel bone ultrasound to measure Broad Band Attenuation (BUA) and Velocity of Sound (VOS). We calculated local costs of pounds sterling 45 for DXA and pounds sterling 15 for QUS. We identified a BUA threshold of 60 dB/MHz as most cost effective as pre-screen, and calculated a sensitivity of 93% and specificity of 84% in identifying those subjects who were subsequently identified as having osteoporosis by DXA. DXA assessment of all patients had a cost of pounds sterling 77 per osteoporotic subject identified. We examined the cost-effectiveness of using QUS as a pre-screen, only referring subjects for more expensive DXA assessment if BUA was less than 60 dB/MHz. However this approach had no advantage, still costing pounds sterling 78 per osteoporotic subject identified. QUS assessment does not appear cost-effective as a pre-screen for DXA, even in this high risk group of women with low trauma Colles' fracture. A QUS pre-screen would only be cost-effective if the scan could be performed at a substantially lower cost.
骨密度（BMD）测量是世界卫生组织（WHO）对骨质疏松症定义方法的核心。双能X线吸收法（DXA）仍然是测量骨矿物质密度（BMD）的金标准技术，但定量超声（QUS）是一种有吸引力的替代骨评估方法，因为它易于使用且相对便宜。有人建议，QUS可作为选择性人群预筛查，以最大限度地提高转诊进行DXA骨密度评估的成本效益。我们着手研究这种方法在评估低创伤性Colles骨折女性中的表现。在46名年龄在50 - 80岁（平均67岁）的女性中，我们使用DXA测量腰椎和髋部的骨密度，并用跟骨超声测量宽带衰减（BUA）和声速（VOS）。我们计算出DXA的本地成本为45英镑，QUS为15英镑。我们确定60 dB/MHz的BUA阈值作为最具成本效益的预筛查指标，并计算出在识别那些随后被DXA确定为患有骨质疏松症的受试者时，其敏感性为93%，特异性为84%。对所有患者进行DXA评估，每识别出一名骨质疏松症患者的成本为77英镑。我们研究了将QUS用作预筛查的成本效益，仅在BUA小于60 dB/MHz时才将受试者转诊进行更昂贵的DXA评估。然而，这种方法没有优势，每识别出一名骨质疏松症患者的成本仍为78英镑。即使在这个低创伤性Colles骨折的高风险女性群体中，QUS评估作为DXA的预筛查似乎也不具有成本效益。只有在扫描成本能大幅降低的情况下，QUS预筛查才具有成本效益。
